There are so many incredible things to see in Galapagos Islands that one must make sure to visit the islands at least once in a lifetime. One of the amazing things that you have the opportunity to see when cruising in the Galapagos Islands, is the fascinating Galapagos tortoise.
The Galapagos tortoises are native to seven of the Galapagos Islands west of the Ecuadorian mainland. The shell shapes and sizes of the tortoises differ between populations depending on the islands that they live on. On the islands with humid highlands the tortoises have a dome shaped shell, they have shorter necks and they are larger. On the other hand, on islands with dry lowlands the tortoises have “saddleback” shells, long necks and they are smaller.
The earliest ancestor of the tortoises was probably of normal size and evolved into the present-day giants after its arrival in Galapagos. This is due to a phenomenon seen in many island ecosystems where gigantism evolves because there is no longer any need to hide from predators and also because there are no other similar animals to compete with for food. Once the tortoises spread around the archipelago, they evolved on their isolated islands into the different races we see today.
The Galapagos Giant Tortoise is probably the most well-known animal of the Galapagos Isles. What’s really fascinating about the Galapagos Giant Tortoises is that they keep growing until they are about 40 – 50 years old and can reach a weight of 500 pounds. The Galapagos Giant Tortoise can grow to be 5 feet tall and this actually makes them the largest tortoises in the world.
Also, the Galapagos Giant Tortoise can actually live for more than 100 years, the oldest recorded tortoise being 152 years old.
The Giant Tortoises are known to belong to just one species, Geochelone elephantopus, with 14 different races or sub-species, four of which are believed to be extinct.
It is possible that all the present races of Giant Tortoise evolved in Galapagos from a common ancestor that arrived from the mainland, floating on the ocean currents.
The environment and climate of the Galapagos Islands differ from island to island. Saddle-backed tortoises generally tend to inhabit the hotter, drier islands with sparse vegetation, while Domed tortoises inhabit the cooler, wetter islands with lush ground vegetation.
Galapagos tortoises are herbivores which means they do not eat meat, only vegetables. Their diet consists mostly of cactus, fruits, vines, grasses and other vegetation. Tortoises can store food and water very efficiently and for a very long time, which means that they are able to go without eating or drinking for up to one year.
Giant Tortoises can also survive for long periods of time in case they are deprived of all liquids, by breaking down their body fat in order to produce water.
Galapagos tortoises are cold-blooded animals, just like other reptiles. They spend much of their day soaking up the sun to warm themselves. But, when the sun goes down and the temperature cools, tortoises sleep partly submerged in mud, water or brush to keep warm. It should also be noted that tortoises are very peaceful creatures.
Mating occurs at any time of the year, however it does have seasonal peaks, generally between January and August. When two mature males meet in the mating season, they will rise up on their legs and stretch up their necks to assess dominance. The shorter tortoise will retreat leaving the taller, larger tortoise to mate with the female. In groups of tortoises from mixed island populations, saddleback males have an advantage over domebacks.
Between June and December, after mating, the females journey several kilometers to reach nesting areas of dry, sandy ground – generally near the coast. Nest digging is an elaborate task and takes several hours, and sometimes spread out even over several days.
Generally between December and April, the young tortoises emerge from the nest 120 to 140 days later and may weigh only 80 grams as well as measure 6 centimeters. What’s really interesting though, is that temperature actually plays a role in the sex of the hatchling: in case the nest temperature is low, more males will hatch; but if the temperature is high, more females will hatch. When the young tortoises emerge from their shells, they must dig their way to the surface, and that can take up to even one month.
Have you ever had the chance to see a Galapagos tortoise? What was your experience in the Galapagos Islands? Please share with us in the comments section below.
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